With its custom replacement glass screen fitted (https://www.ebay.com/usr/virgisst ) I have made some further tests of the recently acquired full plate (10×8 inch) camera (The New Countess). I wanted to test how well the camera could be used with artificial lights since the paper negative responds differently to film.
My first shot was with a short focus length f6.3 lens and an exposure time of 2 seconds. With two large fluorescent bulb lamps, this produced a well-exposed image but the depth of field was very short. To gain depth of field I changed to a lens that went to F64, with a much longer focus length.
However the sliding control moves past the “64” and my first images were way under exposed as the aperture was much less than for F64.
Further test strips gave me an exposure time of 35 minutes. Below are two images; F22 on the left, F64 (+) on the right. The difference in depth of field is evident.
Clearly a 35 minute exposure isn’t appropriate for portraiture. So extra illumination is needed to keep depth of field as great as possible. There is no real substitute for daylight!